This invention relates generally to rolling mills where the rolled products are formed into cylindrical coils. The invention is concerned in particular with a coil handling apparatus and system for receiving such coils at the mill coil forming station and for thereafter transporting the coils in an upstanding condition along a path which subsequent processing operations are performed.
Historically, in earlier rod mills, rod was rolled from two-inch square billets of approximately 30 feet in length, and the resulting product was formed into coils weighing about 400 pounds. These coils, which were about the size and shape of a truck tire, were thereafter transported and cooled on standard overhead hook carriers. However, through the years, there has been a constant demand for larger and larger coils. Thus for example, today's modern rod mill can produce a coil weighing up to 4,250 pounds, whose dimensions are about 331/3 inches I.D., 49 inches O.D., and whose height, before compacting is approximately 112 inches. After compacting, the coil height is reduced by approximately 35% to 73 inches.
In the past, it has been the practice to form these large coils vertically in a reforming tub over a core or sail. After forming, the coils are down-ended 90.degree. from a vertical attitude to a horizontal attitude after which the coils are transferred to hook-carrier systems. Because of the size of the coils now being produced, these systems require very long and sturdy hooks, often with stabilizing rolls and counterweights to control their horizontal attitude. Due to the great height (or length) of the coils, common practice has been to arrange the hooks with their axes normal to the travel direction of the coils. Power-free motion of the hooks has proven to be necessary to permit operations such as trimming, compacting, banding and segregation of the coils while they are being transported. These complicated power-free conveyor systems, which must allow coils to gather in dense accumulations or to run independently of other coils upon demand, require massive overhead supporting structures and tracks.
The weight and size of coils produced by modern mills, when combined with the weight and size of the long carrier hooks employed to transport these coils, now threatens to overtax the load carrying capacity of the standard mass-produced overhead conveyor systems which are universally employed in industry, particularly in foundries and automobile assembly plants. As coil weights continue to increase, these conveyor systems will have to be specially designed, and this will greatly increase their costs to the mill owner. In addition, the supporting structures and rails will also undergo increases in size and costs. These massive steel structures so clutter the coil handling areas that access to coils by overhead cranes is virtually impossible. Moreover, with all of the equipment mounted on an overhead structure, maintenance becomes exceedingly difficult and often quite dangerous. Finally, as coil weights and sizes continue to increase, the danger of coil shape distortion and damage or marking of the product surface becomes an increasingly serious problem which conventional coil handling systems are incapable of coping with. All of these problems point to the need for a better coil handling system with an improved capacity to meet current and future requirements.
It is, accordingly, an object of the present invention to provide a novel and improved coil handling apparatus and system which has the capability of handling the ever increasing coil sizes of modern mills with no appreciable increase in costs for future coils of greater weight.
Another object of the present invention is to entirely eliminate the overhead structures which are common to conventional hook carrier systems, thereby allowing a clear, unobstructed area where cranes, fork lift trucks and the like can readily and safely service the product and the equipment.
Still another object of the present invention is the provision of an improved coil handling apparatus which is easiler and safer to maintain.
Another object of the present invention is the provision of a system and apparatus for handling large product coils in a manner which minimizes coil shape distortion and damage or marking of the surface of the product.
Further objects of the present invention include the provision of a system and apparatus characterized by economy in equipment, building and foundation requirements as well as improved operation and maintenance considerations.